Re: So, is COUNT(*) fast now?

On Fri, Oct 21, 2011 at 3:07 PM, Robert Haas <robertmhaas@gmail.com> wrote:
> [ oprofile results ]

*grovels through the line-by-line results*

Hmm, I guess there is a bit of a hotspot in StoreIndexTuple, which is
probably being folded into IndexOnlyNext in the per-function timings:
   ExecClearTuple(slot);   for (i = 0; i < nindexatts; i++)       values[i] = index_getattr(itup, i + 1, itupdesc,
&isnull[i]);  ExecStoreVirtualTuple(slot);
 

If I'm reading these results right, that section is about 3% of the
total number of samples.

Also, this line is kind of expensive:
       if (!visibilitymap_test(scandesc->heapRelation,                               ItemPointerGetBlockNumber(tid),
                          &node->ioss_VMBuffer))
 

Around 2%.  But I don't see any way to avoid that, or even make it cheaper.

-- 
Robert Haas
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